103 lines
3.2 KiB
Markdown
103 lines
3.2 KiB
Markdown
# NDB Cluster Monitor
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## Overview
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The MySQL Cluster Monitor is a monitoring module for MaxScale that monitors a MySQL Cluster. It assigns a NDB status for the server if it is a part of a MySQL Cluster.
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## Configuration
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A minimal configuration for a monitor requires a set of servers for monitoring and a username and a password to connect to these servers. The user requires the REPLICATION CLIENT privilege to successfully monitor the state of the servers.
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```
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[MySQL Cluster Monitor]
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type=monitor
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module=ndbclustermon
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servers=server1,server2,server3
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user=myuser
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passwd=mypwd
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```
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## Optional parameters for all monitors
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Here are optional parameters that are common for all the monitors.
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### `monitor_interval`
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This is the time the monitor waits between each cycle of monitoring. The default value of 10000 milliseconds (10 seconds) should be lowered if you want a faster response to changes in the server states. The value is defined in milliseconds and the smallest possible value is 100 milliseconds.
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```
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monitor_interval=2500
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```
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### `backend_connect_timeout`
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This parameter controls the timeout for connecting to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 3 seconds.
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```
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backend_connect_timeout=6
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```
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### `backend_write_timeout`
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This parameter controls the timeout for writing to a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 2 seconds.
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```
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backend_write_timeout=4
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```
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### `backend_read_timeout`
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This parameter controls the timeout for reading from a monitored server. It is in seconds and the minimum value is 1 second. The default value for this parameter is 1 seconds.
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```
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backend_read_timeout=2
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```
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## MySQL Cluster Monitor optional parameters
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These are optional parameters specific to the MySQL Cluster Monitor.
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### `script`
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This script will be executed when a server changes its state. The parameter should be an absolute path to the script or it should be in the executable path.
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```
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script=/home/user/script.sh
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```
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This script will be called with the following command line arguments.
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```
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<name of the script> --event=<event type> --initiator=<server whose state changed> --nodelist=<list of all servers>
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```
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### `events`
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A list of event names which cause the script to be executed. If this option is not defined, all events cause the script to be executed. The list must contain a comma separated list of event names.
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```
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events=master_down,slave_down
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```
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## Script events
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Here is a table of all possible event types and their descriptions that the MySQL Cluster monitor can be called with.
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Event Name|Description
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----------|----------
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master_down|A Master server has gone down
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master_up|A Master server has come up
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slave_down|A Slave server has gone down
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slave_up|A Slave server has come up
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server_down|A server with no assigned role has gone down
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server_up|A server with no assigned role has come up
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ndb_down|A MySQL Cluster node has gone down
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ndb_up|A MySQL Cluster node has come up
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lost_master|A server lost Master status
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lost_slave|A server lost Slave status
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lost_ndb|A MySQL Cluster node lost node membership
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new_master|A new Master was detected
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new_slave|A new Slave was detected
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new_ndb|A new MySQL Cluster node was found
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